Tuttle base crack

[outcast]

Have a hairline crack on the fin BASE, ....not the box.
Where the fin is married to the base.

In the box, I probably could still sail it, and it feels solid, The box would keep it together.... but I noticed a difference sailing today when it was loaded...If I really torque on the fin with the base in a vise, the hairline opens a wee bit.

It's a Deboichet...really nice, so well worth the repair time....but I am not sure how to repair....the crack is too small to get epoxy into it....I was thinking of drilling down into the crack....making it bigger but allowing epoxy in just not sure it would make things stronger.

I guess the ultimate would be to re-cast the base.....but that would be a pain...Any suggestions? Thanks

[cgoudie1]

I have a thought, and not much more. If you can get an exacto blade
into the crack, (or use your vise) and open it slightly then you
could apply some acrylic glue (Permabond) which has low enough
viscosity that it would run into the crack. Remove the exacto blade,
and squeeze the base together. That "may" be adequate, and it would
be easy to try.

I also must say that I had a fin with an issue like this (though it had
multiple hairline fractures between the base head and the fin). I ignored
it and in a very powered up run, without hitting anything,
the entire fin sheared off at the head about 2 miles out at a local lake.

-Craig

[outcast]

wow!
unfortunately that confirms my feer that the whole base is probably brittle resin .
I guess it's a complete remold.

[swchandler]

I guess the question can be asked whether your Select fin uses a barrel nut configuration that runs perpendicular through the fin substrate within the base structure, or whether the threads are tapped directly into base like Tectonics fins. If you have the barrel nut design, I'm thinking that if you remove one you'll find out if the mounting is solid. If you do have a solid connection with the internal fin substrate, the final base shape is created simply to fill the cavity, and you have little chance of losing the fin, particularly if you have a good fit and it's a Tuttle box. A Powerbox design would be a bit more questionable with a single screw attachment, but it still should be viable.

If you're facing trying to remove and re-construct the existing base, I'm thinking that scrapping the fin and replacing it would be the route that I would probably take. It would be quite a job to go the re-base route, as it would require building a fixture to form, hold and align the fin substrate perfectly. If you have an old board with the same kind of finbox to work with, it could make the job easier to accomplish, yet getting the mold release part of the equation to work out easily might be a tough task.

Before starting any major re-base plan, I would definitely give Craig's plan a try.

[outcast]

I appreciate the help and thoughts!

I will remove the barrel nut, i think that's a good idea. The screws go to barrel nuts, not threaded to base, but i think the barrel nuts aren't neccessarily married to the fin directly, and the fin may "float" in the base resin

I wish i knew what the fin core at this area was....carbon or foam...i bet foam

I get the sense that at the nut level things are fine, and i am contemplating shaving off a thick layer of the base "above" the nuts (Closer to the working fin/ water), and then glassing the sides of the shave ....In other words replace as much of the filler as possible

That way i don't really have to mess with a template mold/ redrilling nuts etc, just the thickness....Obviously get to as much a one-piece base as possible....but preserve the nut holes and side template

Have access to a CNC router that could help take it down evenly

would prefer to overbuild now rather than just fill the cracks...in part cause i want to do it once....i hear you on the alignment issues

[bred2shred]

Got a pic?

What about drilling a countersunk hole through the base, then spread the crack open and inject epoxy into the crack, then screw the sides of the base together using a stainless steel flat head wood screw (countersunk)?

sm

[DanWeiss]

Outcast, if the crack runs parallel to the chord at the very base of the fin right where it turns into the actual head, or "base" you take your chances. As you know, the root of the fin takes the most stress. Many dear fins have found eternity with da' fishes at the most inconvenient times. Not fun.

If the crack is inside the base itself, I wouldn't worry too much about it. A Tuttle base (again, as you know) uses parallel sides that should fit very tightly. The fin bolts/screws should only draw the fin into the box working against that tight fit. All that tightness should hold a fin fairly securely, even if you removed the bolts before sailing. That's more true with deep Tuttle boxes rather than standard, but still should be applicable with properly fitting fin.

For giggles, I would drill diagonally from the base into the fin, crossing the crack. You will then see what material lies beneath. Foam or otherwise, it doesn't matter since the epoxy poured into the hole will grip the carbon/glass/G-10 anyway just as it did in manufacturing.

My advice is always free, so you get what you pay for.

[joethewindsufa]

wow - serendipity
happened to me just last weekend
powerbox select 48 cm fin - cracks at the head
always inspect when i get off the water and that was what i saw
cracks in the "plastic"
had the same idea that epoxy, marinetex, etc would NOT get in
applied the waterproof glue that I use
today put in in the board and applied some pressure - seems ok
will i take it out in gusty conditions - NOT
not sure it was when i hit the sandbank or when i kicked the fin by accident
NEVER happened to me before

[outcast]

I'm pretty sure that the base poxy on mine is just old/stress cracked.
It's not bad now, but ...

I have come to a decision that i will rout a 3/4 inch band around the circumference of the base, and fill with a carbon cloth wrap around.....then i just have to sand down to the existing lines

In essence, this will allow me to re-cast the base but keep the outline shape/nuts intact....it's kind of a pita
Powerbox would be harder because of the taper. but maybe easier to mold with one nut

I'll follow up with a pic when done

In the meantime i bought 2 replacement deboichets from our buy-sell classifieds, and they were worth it!